Biopsies are fundamental to the diagnosis, management and treatment of most cancers. A tissue sample enables a pathologist to make a diagnosis of cancer, to determine its type and nuclear grade, and to evaluate for cancer specific biomarkers that affect the plan of action for treatment. To obtain this information, the pathologist needs an adequate specimen of tissue from the lesion in question. Imaging guidance (ultrasound, x-ray or MRI) is used to identify and help sample the lesion. Despite imaging guidance, up to 12% of image-guided needle biopsies are non-diagnostic. Non-diagnostic biopsies result from not sampling the lesion or sampling non-viable portions of the lesion. This project will supplement current biopsy techniques by providing real-time non-destructive optical sampling at the tip of the biopsy needle to enable the operator to locate and sample from the most cellular and most suspicious areas of a lesion. Specifically, this system detects areas of high cellularity (i.e. higher DNA content in a specific volume), increased blood content, and decreased oxygen saturation, which are all associated with malignant cells. This is accomplished by placing a fiber optic based device inside a standard stylet needle, which is routinely used during biopsies. This approach takes advantage of the intrinsic optical contrast between benign and malignant tissue. No intravenous exogenous contrast agent is needed. An easy to understand series of light indicators will provide real-time assessment of the tissue at the tip of the biopsy needle while the operator is guiding the needle toward the lesion of interest. This will direct the operator to place the biopsy needle at the most-suspicious and most cellular parts of the lesion. Using this system, it is expected to decrease the non-diagnostic biopsy rate, allowing earlier and more definitive diagnoses and decreasing anxiety and complications from re-biopsies.